In liquid crystal displays, in order to arrange liquid crystal molecules regularly, it is necessary to provide an alignment film. At present, alignment films are mostly produced by a rubbing method. In the rubbing method, a rubbing cloth is placed on a rubbing roller of an alignment processing device, and a series of small grooves regularly arranged toward a particular direction on a PI (Polyimide) film are produced using fluffs of the rubbing cloth. If the quality of the rubbing cloth is defective, it will lead to formation of irregularly arranged grooves or traces on the surface of the produced PI film, thus affecting the regular arrangement of liquid crystal molecules, and ultimately leading to display defects in the liquid crystal display and low yield of products. Therefore, the quality of the rubbing cloth directly affects the quality of the alignment film.
After the rubbing cloth is placed on the rubbing roller, detection is performed on the rubbing cloth before put it into operation. At present, a conventional detection method is to coat a PI film on a glass substrate specifically designed for the detection, and to rub the PI film with the rubbing cloth on the rubbing roller and perform a rubbing alignment process. Then, the processed glass substrate is subjected to water vapor spraying and light irradiation, and the quality of the rubbing cloth is judged by an engineer on the basis of the traces on the PI film. In practice, it is required to remove the coated PI film the glass substrate for detection after each test, and then put the glass substrate into operation again. It will occur a quality defect which disturbs the judgment of the engineer on the glass substrate after it is repeatedly utilized. So this method fails to effectively detect the quality of the rubbing cloth. In addition, the cost of the detection method is high.
It should be noted that, information disclosed in the above background portion is provided only for better understanding of the background of the present disclosure, and thus it may contain information that does not form the prior art known by those ordinary skilled in the art.